scholarly journals Array Gain of a Linear Array in an Ocean Waveguide

2021 ◽  
Vol 11 (11) ◽  
pp. 5046
Author(s):  
Zong-Wei Liu ◽  
Chun-Mei Yang ◽  
Ying Jiang ◽  
Lei Xie ◽  
Jin-Yan Du ◽  
...  
Keyword(s):  
Transmission Loss ◽  
Spatial Coherence ◽  
Correlation Coefficients ◽  
Channel Correlation ◽  
Acoustic Channel ◽  
Physical Mechanisms ◽  
Channel Characteristics ◽  
Special Case ◽  
Array Gain ◽  
Insight Into

Array gain is investigated based on the acoustic channel characteristics manifested by the fluctuant transmission loss and decrease in the acoustic channel spatial coherence. An analytical expression is derived as the summation of the products of the acoustic channel correlation coefficients and root-mean-square pressures. The formula provides insight into the physical mechanisms of the gain degradation in the ocean waveguide. Furthermore, this formula provides a new method to study array gain in the ocean waveguide from underwater acoustic field. The obtained expression is a more general formula that is applicable to shallow water, deep sea, and continental slope, with the traditional methods as a special case. Numerical results show that the array gain calculated by previous formulas are generally overestimated, caused by ignoring the effect of transmission loss fluctuation.

Current-Signature-Based Analysis of Complex Test Fails

1999 ◽  
Author(s):  
Anne E. Gattiker ◽  
Phil Nigh ◽  
Wojciech Maly
Keyword(s):  
Failure Analysis ◽  
Physical Nature ◽  
Channel Length ◽  
Test Methods ◽  
Multiple Test ◽  
Physical Mechanisms ◽  
Test Behavior ◽  
Complex Test ◽  
Current Signature ◽  
Insight Into

Abstract This article provides an analysis of a class of failures observed during the SEMATECH-sponsored Test Methods Experiment. The analysis focuses on use of test-based failure analysis and IDDQ signature analysis to gain insight into the physical mechanisms underlying such subtle failures. In doing so, the analysis highlights techniques for understanding failure mechanisms using only tester data. In the experiment, multiple test methods were applied to a 0.45 micrometer effective channel length ASIC. Specifically, ICs that change test behavior from before to after burn-in are studied to understand the physical nature of the mechanism underlying their failure. Examples of the insights provided by the test-based analysis include identifying cases where there are multiple or complex defects and distinguishing cases where the defect type is likely to be a short versus an open and determining if the defect is marginal. These insights can be helpful for successful failure analysis.

scholarly journals Secular Mass Loss from Cataclysmic Variables

1977 ◽  
Vol 42 ◽  
pp. 365-370
Author(s):  
Józef Smak
Keyword(s):  
Mass Transfer ◽  
Angular Momentum ◽  
Chemical Composition ◽  
Mass Loss ◽  
Cataclysmic Variables ◽  
Dynamical Evolution ◽  
Good Insight ◽  
Physical Mechanisms ◽  
Cataclysmic Binaries ◽  
Insight Into

The mass loss from cataclysmic binaries seems an important and worth studying phenomenon for a number of reasons. It is probably enough to mention only two of them:(a) Whenever we can directly observe the ejected material, determine its amount and the rate of mass loss, as well as its chemical composition (this being the case of the expanding envelopes of novae), we are getting a good insight into the basic physical mechanisms responsible for the observed phenomena.(b) The mass loss (together with the mass transfer) and the loss of the orbital angular momentum are related directly to the dynamical evolution of a binary system and - indirectly - to the evolution of its components.

Sound Transmission Through Simply Supported Finite Double-Panel Partitions With Enclosed Air Cavity

2010 ◽  
Vol 132 (1) ◽  
Author(s):  
F. X. Xin ◽  
T. J. Lu ◽  
C. Q. Chen
Keyword(s):  
Sound Velocity ◽  
Velocity Potential ◽  
Transmission Loss ◽  
Elevation Angle ◽  
Sound Transmission ◽  
Double Fourier Series ◽  
Potential Method ◽  
Air Cavity ◽  
Simply Supported ◽  
Physical Mechanisms

The vibro-acoustic performance of a rectangular double-panel partition with enclosed air cavity and simply mounted on an infinite acoustic rigid baffle is investigated analytically. The sound velocity potential method rather than the commonly used cavity modal function method is employed, which possesses good expandability and has significant implications for further vibro-acoustic investigations. The simply supported boundary condition is accounted for by using the method of modal function and the double Fourier series solutions are obtained to characterize the vibro-acoustic behaviors of the structure. The results for sound transmission loss, panel vibration level, and sound pressure level are presented to explore the physical mechanisms of sound energy penetration across the finite double-panel partition. Specifically, focus is placed on the influence of several key system parameters on sound transmission including the thickness of air cavity, structural dimensions, and the elevation angle and azimuth angle of the incidence sound. Further extensions of the sound velocity potential method to typical framed double-panel structures are also proposed.

scholarly journals Special train algebras arising in genetics II

1965 ◽  
Vol 14 (4) ◽  
pp. 333-338 ◽  
Author(s):  
Harry Gonshor
Keyword(s):  
New Method ◽  
Binomial Coefficients ◽  
Primary Concern ◽  
Multiple Alleles ◽  
Special Train ◽  
Special Case ◽  
Insight Into

We shall extend some of the results of (7) to the case of multiple alleles, our primary concern being that of polyploidy combined with multiple alleles. Generalisations often tend to make the computations more involved as is expected. Fortunately here, the attempt to generalise has led to a new method which not only handles the case of multiple alleles, but is an improvement over the method used in (7) for the special case of polyploidy with two alleles. This method which consists essentially of expressing certain elements of the algebra in a so-called “ factored ” form, gives greater insight into the structure of a polyploidy algebra, and avoids a great deal of the computation with binomial coefficients, e.g. see (7), p. 46.

scholarly journals Effective Markovian description of decoherence in bound systems

2014 ◽  
Vol 92 (2) ◽  
pp. 168-178 ◽  
Author(s):  
A.S. Sanz
Keyword(s):  
Degrees Of Freedom ◽  
Energy Levels ◽  
Dynamical Process ◽  
Initial State ◽  
Physical Mechanisms ◽  
State Diffusion ◽  
Decoherence Rate ◽  
Quantum State Diffusion ◽  
Insight Into ◽  
Good Agreement

Effective descriptions accounting for the evolution of quantum systems that are acted on by a bath are desirable. As the number of bath degrees of freedom increases and full quantum simulations turn out computationally prohibitive, simpler models become essential to understand and gain an insight into the main physical mechanisms involved in the system dynamics. In this regard, vibrational decoherence of an I2 diatomics is tackled here within the framework of Markovian quantum state diffusion. The I2 dynamics are analyzed in terms of an effective decoherence rate, Λ, and the specific choice of the initial state, in particular, Gaussian wave packets and two-state superpositions. It is found that, for Markovian baths, the relevant quantity regarding decoherence is the product of friction (η) and temperature (T); there is no distinction between varying one or the other. It is also observed that decoherence becomes faster as the energy levels involved in the system state correspond to higher eigenvalues. This effect is due to a population redistribution during the dynamical process and an eventual irreversible loss of the initial coherence. These results have been compared with those available in the literature from more detailed semiclassical IVR simulations, finding a good agreement.

Rotatability Laws for N-Bar Kinematic Chains and Their Proof

1991 ◽  
Vol 113 (1) ◽  
pp. 32-39 ◽  
Author(s):  
Kwun-Lon Ting ◽  
Yung-Way Liu
Keyword(s):  
Valuable Insight ◽  
Kinematic Chains ◽  
Special Case ◽  
Insight Into

This paper presents a thorough proof and adds valuable insight into the theorems [1] concerning the mobility of planar N-bar linkages. The paper includes four parts: the assemblability, the revolvability between two links, the full rotatability, and the classification. The proof is based on the assemblability condition of N-bar linkages and the revolvability condition of an angle. Examples are also provided to further clarify the use of these theorems. In these theorems, Grashof’s Law becomes a very special case.

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